Antioxidant



. diene.

Patented June 1, 1943 ANTIOXIDANT Philip T. Paul. Naugatuck, 001111., assignor to United States Rubber Company, New York, N. Y., a corporation of New Jersey ,No Drawing. Application April 30, 1941,

Serial No. 391,144

Claims.

This invention relates to improvements in anti-oxidants.

An object of the invention is to provide chemicals for retarding the deterioration of rubber, natural or artificially prepared. A further object of the invention is to provide chemicals whichadditionally act as flex improvers or anti; flex cracking agents for vulcanized rubber such as tire treads, which undergo repeated strains during use. Further objects will be apparent from the following description.

According to the invention, the rubber composition has incorporated therein a product of reaction of a polyhydric phenol and an aliphatic Exemplary of polyhydric phenols that may be reacted with the dienes are:

Hydroquinone Resorcinol Catechol Pyrogallol Phlorglucinol Toluhydroquinone 2,5 dihydroxy biphenyl 1,4 dihydroxy naphthalene 2,5 dihydroxy ethyl benzene Pyrogallol monomethyl ether -2,5 dihydroxy diphenyl ether 2,5 dihydroxy diphenyl sulfide Dithiohydroquinone Mono thio hydroquinone 2-aliyl 1,4 dihydroxybenzene -2-methallyloxy, 1,4 dihydroxy benzene Z-dimethyl amino 1,4 dihydroxy benzene 2-methyl phenyl amino 1,4 dihydroxy benzene 2-chloro 1,4 dihydroxy benzene -phenyl catechol Examples oi aliphatic dienes that may be reacted with any of the above polyhydric phenols for the purposes of the invention are:

Butadiene Isoprene 2,3 dimethyl 1,3 butadiene 1,3 dimethyl 1,3 butadiene 1,1 dimethyl 1,3 butadiene 1,2 diethyl 1,3 butadiene 1,5 hexadiene 1,6 heptadiene 1,4 dimethyl 1,3 butadiene 1 phenvl 1,3 butadiene 2 phenyl 1,3 butadiene 2 para tolyl 1,3 butadiene 1 paraxenyl 1,3 butadiene 1,4 pentadiene 1 vinyl 1,3 butadiene Cyclopentadiene Cyclohexadiene can be readily incorporated in rubber. They are very soluble in rubber and may be' used in large amounts with substantially no danger of blooming to the surface.

The constitution of the reaction products is unknown, but it is believed that they contain an appreciable amount of heterocyclic substances of chromane and/or coumarane structures. In the case of hydroquinone and butadiene the reaction may be HO +CHFCHCH=CH1 A mixture or C C H g C H C H) CHfl JE H:

Cg Benzo-p-di-2 methyl chromane CH-CH:

cfi.

2-methyl B-hydrory chromano E H0 on HI I I i-methyl (i-hydroxy chromane CHCH1CH:

no m

Z-ethyl 6 hydroxy coumarana O a CH cncmcm CIHJlH o/ H: Benzo p-di 2 ethyl coumarane CHCHi' H0 HOH:

2,3 dimethyl 5 hydroxy coumarane Iodine Bromine Chlorine Hydriodic acid Hydrobromic acid Hydrochloric acid Sulfuric acid Oxalic acid Calcium chloride Aluminum chloride Ferrous chloride Hydrofluoric acid Succinlc acid Chromic chloride Manganese chloride .Acid activated Bleaching earths The following examples are given to illustrate the preparation of the chemicals, and the efiectiveness of their use in rubber. The parts are by weight:

Example 1 Hydroquinone (25 grams), 1,3 dimethyl 1,3 butadiene (38.6 cc.) are refluxed in 100 cc. acetic acid with 5 grams zinc chloride for 15 hours. After cooling benzene is added and the mixture extracted several times with water. The benzene solution is dried and the benzene removed by distillation. The residue from the distillation is a heavy syrup, boiling point 80-260 C. at 3 mm. mercury pressure.

Example 2 Catechol (25 grams) is reacted with 1,3 dimethyl 1,3 butadiene as in Example 1. The product distills 75-220" C. at 3 mm. mercury pressure.

Example 3 Resorcinol (25 grams) is reacted with 1,3111- methyl 1,3 butadiene as in Example 1. The product distilis 130-185 C. at 3 mm. mercury pressure.

Example 4 Pyrogallol (39 grams) is reacted with 1,3 dimethyl 1,3 butadiene as in Example 1. The product; distills 135-200 C. at 2 mm. mercury pressure.

Example 5 Hydroquinone (22 grams) and 26.4 grams dicyclopentadiene are refluxed in cc. acetic acid with 5 grams zinc chloride for 15 hours. The product is isolated as in Example 1. 0n vacuum fractionation two products are obtained.

I. Boiling range 100-300' C. at 3 mm. II. Residue-a solid-melting range -155" C.

Example 6 A mixture of 33 grams hydroquinone, 21 grams isoprene. 33 cc. acetic acid and 3 grams zinc chloride is heated in a sealed tube over night at 130 C. The product is isolated as described in Example 1, except that it is not distilled.

Example 7 A mixture of 18.3 grams hydroquinone, 9 grams butadiene, 30 cc. acetic acid and 2 grams zinc chloride are heated in a sealed tube over night at 130 C. The product is worked up as described .in Example 1. It is suitable as such for use in rubber without a distillation.

,The materials are tested in a white molded stock or the composition:

The anti-oxidant to be. tested is incorporated in the ratio of one (1.0) part to one hundred (100)-parts of pale crepe. Cures are made for 10, 20, 30 minutes at 30 pounds per square inch steam.

The following data shows the tensile and elongation at break before and after ageing 96 hours in oxygen under 300 pounds per square inch pressure.

0 t so lb I i t i l f are a 5. sq. n. s earn et y pressure Control 1,3 butadiene reaction product Unaped Aged 10 mins Failed 2080-680 20 mins Faile 1040-653 Failed 1000-613 Pers iet yi Control 1,3 butadiene reaction product Unaged 10 mins 2510-090 2000-713 20 mins 30-080 2210-733 30 mins 2120-683 2130-730 Aged Failed 1640-710 Failed 1470-680 Failed 1220-000 A It is to be uno'srstood that the invention may be applied to the preservation 01' natural a raw Cure at so lbalsq. in. steam pressure Control i'g g g reaction product Unwed 10mins 2510-690 2290-690 2) mins 2130-680 2260-700 30mins 2120-683 2130-703 Aged Failed 1310-656 Failed 490-490 Failed 370-163 Pyrogalloll 3 dimethyl Comm! 1:8 butadiene reaction product- Unoqed 10 mins 2610-690 2450-72) in ZED-680 2160-703 so $1 1: 21W 2140-730 mins a 1610-663 10 a e 2) mins Failed 1490-666 3) mins Failed 1230-650 Hydroquinone- Control dicyclo" tadiene volat fraction 1 mins 2700-140 2? mins 2610-700 8) nine 2370-686 10 mins 2000-660 21mins 1560-626 so mine 800-546 Hydroquinonedicyclopentadiene Control non-volatile iraction H droquinone- Cure at 30 lba/sq. in. steam Control y mane p reaction product Unaged Aged 620-490 mac-an Failed 1840-636 Failed 1380-606 Hydroquincnc- Control butadiene reaction product Unagr 1612 5.... M6 2740-700 20 i. 3: mins l 2860-670 2260-860 1 Aged 20 mi. s l 800-606 1720-643 2-) 21mg. l i 4 Failed "60-643 32-min! Failed East-n06 ample, there may be incorporated other accelerators, softeners, etc.

The anti-oxidant may be incorporated in any type of rubber composition such as those used for automobile tires and tubes, hose, belting, sheet and thread rubber, rubberized fabrics, molded goods, boots and shoes, etc. where vulcanized in a mold, in open steam, in hot air, or in the cold by the so-called acid process. The proportion of the anti-oxidant may vary from about 0.1% to 5%, although either. smaller or greater proportions may be found useful. It the material to which it is added is a liquid such as rubber cement the anti-oxidant may be dissolved there in a suitable small proportion. The anti-oxidant may beincorporated into solid rubbers by milling or mastication and prepared for incorporation into dispersions or solutions either in powder, paste, or solutionrorm, or applied in such forms for incorporation by difiusion to the surfaces of vulcanized or unvulcanized rubber oods.

Having thus described my invention, what I claim and desire to protect by Letters Patent is:

1. The method 01' preserving rubber compositions which comprises incorporating therein a product of acid-catalyzed reaction of a polyhydric phenol and an aliphatic diene hydrocarbon.

tions which comprises incorporating therein a product of acid-catalyzed reaction of a polyhydric phenol and 2-, methyl 1,3 butadiene.

5. The method oi. preserving rubber compositions which comprises incorporating therein a product or acid-catalyzed reaction of a polyhydric phenol and a dicyclopentadiene.

6. The method or preserving rubber compositions which comprises incorporating therein a product of acid-catalyzed reaction of hydroquinone and an aliphatic diene hydrocarbon.

'a. The method of preserving rubber compositions which comprises incorporating therein a product or acid-catalyzed reaction of hydroquinone and a monomeric 1,3-butadiene hydrocarhon.

8. The method of preserving rubber compositions which comprises incorporating therein a product of acid-catalyzed reaction oi hydroquinone and a dicyclopentadiene.

9. A rubber composition containing a product or acid-catalyzed reaction or a polyhydric phenol and an aliphatic diene hydrocarbon.

10. A rubber composition containing a product of acid-catalyzed reaction or a polyhydric phenol and a monomeric 1,3-butadiene hydrocarbon.

PHILIP T. PAUL. 

